Stoke-on-Trent tremor 'had 1.7 magnitude'
A tremor in part of Stoke-on-Trent had a magnitude of 1.7, the British Geological Survey says.
The incident happened on Sunday morning near the site of the former Hem Heath Colliery.
Dr Ian Stimpson, a senior lecturer in Geophysics at Keele University, said collapsing mineshafts have caused tremors in the past.
He has described the incident, which is not thought to have caused any damage, as "small and local".
"Earthquakes are entirely unpredictable," he said.
"Back in 2009, we had four small events over about a month.
"But, whether we will have any more or this is an isolated event, it's impossible to say at this point."